Mobile radio devices or user equipment UE are extensively tested in the field, i.e. in public radio networks. The public radio networks can comprise cellular networks comprising a plurality of cells. However, such in-field tests are time-consuming and thus expensive. During the in-field test, the device under test communicates with base stations of the cellular network. The device under test receives downlink messages transmitted by base stations of the public radio network and can transmit itself uplink messages back to the base stations. Accordingly, during the in-field test, protocol messages are exchanged between the mobile radio device under test and other entities of the network system. The device under test can write during the in-field test one or more field test log files. For instance, it is possible to generate in-field log files by a log recorder connected to the device under test during the in-field test. These recorded field test log files are in a conventional system analyzed manually to extract causes of an observed behavior of the device under test during the field test. The test authorizing software can then be used to create a similar test which may be run on a network simulator. This test is then refined until a similar behavior is observed in the test laboratory.